Field experiments for alfalfa weevil control conducted in Siskiyou and Lassen counties during 1964–65 indicate little likelihood of replacing the no longer recommended cycladiene insecticides (such as heptachlor or dieldrin) with other materials for dormant season application. However, several new insecticides, applied as sprays for larval control on the growing crop, were found superior to spray materials now in use. This is a progress report of research; only a few of the materials mentioned in the text and tables are registered or recommended by the University of California. See U.C. Pest and Disease Control Guide For Alfalfa Hay, Leaflet 85, for recommendations.